Seasonal Variation of Urinary Bisphenol a Concentrations Measured on Multiple Consecutive Days in a Prospective, Pre- Conception CohortAbstract Number:1693 Christina Porucznik*, Kyley Cox, Nicole Bailey, Joseph Stanford, James VanDerslice, Diana Wilkins, Eric Brozek, David Anderson Christina Porucznik* University of Utah Division of Public Health, United States, E-mail Address: [email protected] Search for more papers by this author , Kyley Cox University of Utah Division of Public Health, United States, E-mail Address: [email protected] Search for more papers by this author , Nicole Bailey University of Utah Division of Public Health, United States, E-mail Address: [email protected] Search for more papers by this author , Joseph Stanford University of Utah Division of Public Health, United States, E-mail Address: [email protected] Search for more papers by this author , James VanDerslice University of Utah Division of Public Health, United States, E-mail Address: [email protected] Search for more papers by this author , Diana Wilkins University of Utah Center for Human Toxicology, United States, E-mail Address: [email protected] Search for more papers by this author , Eric Brozek University of Utah Center for Human Toxicology, United States, E-mail Address: [email protected] Search for more papers by this author , and David Anderson University of Utah Center for Human Toxicology, United States, E-mail Address: [email protected] Search for more papers by this author AbstractBackground: Bisphenol A (BPA) is an endocrine disrupting chemical found in canned food and other consumer products. BPA has been detected in human specimens throughout the world and at levels similar to those associated with adverse reproductive outcomes in animal models. Objective: To examine and compare the distribution of urinary BPA concentrations collected from partners of a male-female couples by month of collection.Methods: A prospective, pre-conception cohort of couples (women 18–35, men 18–40) was recruited in Utah beginning in early 2012. Recruitment is ongoing. Couples observed cervical mucus to identify the fertile window. Participants collected first-morning urine samples beginning during the fertile window, after which men discontinued collecting but women collected for the remainder of the cycle. BPA was measured in each urine sample using quantitative LC-MS. Geometric means (GM) with 95% confidence intervals (CI) for BPA concentrations were calculated. A mixed model was generated on log-transformed BPA values to calculate differences between geometric least squares means applying Tukey-Kramer multiple comparison tests and adjusted p values.Results: BPA concentrations were highest in May (GM 2.70 ng/mL, 95% CI 2.30, 3.17) and June (GM 2.78 ng/mL, 95% CI 2.46, 3.14) followed closely by the winter months November (GM 2.67 ng/mL, 95% CI 2.31, 3.11), December (GM 2.62 ng/mL, 95% CI 2.26, 3.11), and January (GM 2.66 ng/mL, 95% CI 2.30, 3.07). After controlling for participant age and time between specimen collection and analysis, specimens collected in August (GM 1.28 ng/mL, 95% CI 1.09, 1.51) were significantly lower compared to May-July, Oct and Nov (p<.01). June was significantly higher compared to Jan-April, July, and Aug (p 0.04).Conclusions: These preliminary findings suggest that BPA exposure varies by month, perhaps because of differences in availability of fresh foods compared to packaged foods.